body, html 
    line-height: 1
    font-weight: 200
    font-family: 'PingFang SC','STHeitiSC-Light','Helvetica-Light',arial sans-serif

border-1px($color)
    position relative
    &:after
        display: block
        position absolute
        left 0
        bottom 0
        width 100%
        border-top 1px solid $color
        content ''
border-none()
    &:after
        display: none

bg-image($url)
    background-image: url($url + "@2x.png")
    @media (-webkit-min-device-pixel-ratio: 3), (min-device-pixel-ratio: 3) 
        background-image:  url($url + "@2x.png")